纤维复合精铸硅溶胶型壳的高温蠕变行为及增强机制

Investment casting technology has been utilized increasingly due to the great flexibility provided for producing complicated parts nearer to net shape, enabling customers to optimize designs and reduce weight and cost, all of which are vital, especially in aeronautical and automotive industries. But the insufficient, such as long period of production shell, low green strength, slowly rejection of heat, expensive and complex casting cleaning operation for high retained strength of shell and a great environmental pressure for excessive discharge of waste shell with large wall thickness, were limited its application widely. This project is look forward to improve the properties of investment casting shell which is dependent on fiber reinforced polymer/plastic. The effects of variety and content of fibers on properties of shell will be investigated in this work. The deformational behavior at high temperature and mechanism of fiber reinforced shell will also be analyzed. At the same time, Looking for the suitable manufacturability of fiber reinforced that can obtain the investment shell with high properties. The main objective of this project are defined the mechanism and the deformational behavior at high temperature of fiber reinforced shell clearly, and figure out the influence and the manufacturability on content of different fibers. Through this research, we are expecting to reduce the insufficient on big part which is produced by investment casting and limited by poor performance. The development and employment of fiber reinforced investment casting shell have a great significance for aviation and aerospace industry.

熔模精密铸造是一种能够实现少切削或无切削加工的液态金属成形技术，在生产制造领域，尤其是航空、航天部件的生产中应用广泛。但由于其制壳周期长、湿强度建立慢，常温强度低、浇注后的散热较慢、残留强度高、铸件清理困难及环保压力大等不足，限制了其更广泛的应用。本项目针对熔模铸造用硅溶胶型壳性能的不足，提出纤维复合技术来增强型壳，通过对型壳各项性能的综合研究，寻找合适的纤维复合工艺，获得综合性能优异的精铸用型壳，并对纤维复合型壳的增强机理及在高温下的变形行为进行研究。主要目标是揭示纤维在复合型壳中的增强机理及高温时纤维复合型壳的变形机制，明晰纤维的种类及加入量对型壳性能的影响规律，形成完整成熟的纤维复合精铸型壳制备工艺。通过本项目研究期望减少熔模铸造技术在大型件或其它铸件生产时由于其性能不足所受的限制。纤维增强型壳的开发及使用对我国航空、航天及民用器件的精密铸造成型具有重要意义。

熔模精密铸造是一种能够实现少切削或无切削加工的液态金属成形技术，在生产制造领域，尤其是航空、航天部件的生产中应用广泛。但由于其制壳周期长、湿强度建立慢，常温强度低、浇注后的散热较慢、残留强度高、铸件清理困难及环保压力大等不足，限制了其更广泛的应用。本项目针对熔模铸造用硅溶胶型壳性能的不足，提出纤维复合技术来增强型壳，通过对型壳各项性能的综合研究，寻找合适的纤维复合工艺，获得综合性能优异的精铸用型壳，并对纤维复合型壳的增强机理及在高温下的变形行为进行研究。项目共取得以下重要研究结果：对焙烧工艺的研究结果表明，在950℃的焙烧温度及90min焙烧时，型壳的焙烧后强度为4.12 MPa，与其他焙烧温度下的型壳相比，强度最大；采取纤维分散工艺实现纤维增强作用的研究表明分散剂可以有效得提升纤维在涂料中的分散性，同时，由于分散剂本身的增稠作用，导致涂料的性能和粘接能力都发生了改变；在纤维铺放装置中，通过空气的流动，纤维可以均匀地铺放在型壳表面，从而提高了型壳强度。钢纤维作为复合纤维，对复合型壳的高温强度和高温散热性研究表明，钢纤维加入到涂料中后，所制备的型壳在高温服役时，由于纤维依然存在于型壳中，其增强效果较好，尤其在1200℃时，型壳具有较高的强度，采用钢纤维复合制备型壳时，由于纤维的良好导热性能，使得浇注金属液后铸件更易于冷却，型壳的散热能力得到提升。上述研究成果的取得，涵盖了熔模铸造型壳的从制备到使用的各个环节所需的性能指标，对熔模铸造用型壳的强度、高温变形、透气性、散热能力、溃散性都进行了系统的研究，并获得综合性能优异的熔模铸造用型壳，并对其增强理论和高温服役时蠕变机制和浇注过程中的换热行为进行了深入的理论分析和探讨，形成了相关机制。纤维增强型壳的开发及使用对我国航空、航天及民用器件的精密铸造成型具有重要意义。